1. Field of the Invention
This invention relates to compounds and methods for the treatment of cancer. In particular, the invention provides compounds that inhibit Aurora kinase enzymes, pharmaceutical compositions comprising the compounds, and methods of using the compounds for the treatment of cancer.
2. Background of the Invention
According to the American Cancer Society, an estimated 1.4 million Americans were newly-diagnosed with cancer in 2004 and about 560,000 victims died from the disease. While medical advance have improved cancer survival rates, there is a continuing need for new and more effective treatment.
Cancer is characterized by uncontrolled cell reproduction. Mitosis is a stage in the cell cycle during which a series of complex events ensure the fidelity of chromosome separation into two daughter cells. Several current cancer therapies, including the taxanes and vinca alkaloids, act to inhibit the mitotic machinery. Mitotic progression is largely regulated by proteolysis and by phosphorylation events that are mediated by mitotic kinases. Aurora kinase family members (e.g., Aurora A, Aurora B, Aurora C) regulate mitotic progression through modulation of centrosome separation, spindle dynamics, spindle assembly checkpoint, chromosome alignment, and cytokinesis (Dutertre et al., Oncogene, 21: 6175 (2002); Berdnik et al., Curr. Biol., 12: 640 (2002)). Overexpression and/or amplification of Aurora kinases have been linked to oncogenesis in several tumor types including those of colon and breast (Warner et al., Mol. Cancer Ther., 2: 589 (2003); Bischoff et al., EMBO, 17: 3062 (1998); Sen et al., Cancer Res., 94: 1320 (2002)). Moreover, Aurora kinase inhibition in tumor cells results in mitotic arrest and apoptosis, suggesting that these kinases are important targets for cancer therapy (Ditchfield, J. Cell Biol., 161: 267 (2003); Harrington et al., Nature Med., 1 (2004)). Given the central role of mitosis in the progression of virtually all malignancies, inhibitors of the Aurora kinases are expected to have application across a broad range of human tumors. There is thus a need for new Aurora kinase inhibitors.